In the following months, stories emerged depicting a toxic sales culture and employee mistreatment. Some former employees told CNNMoney they were subject to retaliation after they tried to stop the sales tactics.

Since the scandal came to light, Wells Fargo has been under investigation by the Department of Justice, Congressional committees, state attorneys general and prosecutors offices. Customers, employees and shareholders have also launched class-action lawsuits against Wells Fargo.

The company's board of directors also opened an independent investigation into the practices. In a news release Tuesday, Wells Fargo said that investigation is expected to finish before the bank's annual shareholder meeting in April.

Wells Fargo identified the four employees it fired as:

- Claudia Russ Anderson, former community bank chief risk officer.

- Pamela Conboy, Arizona lead regional president.

- Shelley Freeman, former Los Angeles regional president.

- Matthew Raphaelson, head of community bank strategy and initiatives.